The time limit for filing all Medicare fee-for-service claims (Part A and Part B claims) is 12 months, or 1 calendar year from the date services were furnished.

The "Through" date on claims will be used to determine the timely filing date. Example: A claim has a From date of 7/1/2012 and a Through date of 7/31/2012. The claim must be received by 7/31/2013.

References:  

http://www.cms.gov/Regulations-and-guidance/Guidance/Transmittals/downloads/R2140CP.pdf

MEDICARE - HOSPICE:

Home health and hospice billing transactions, including claims, and adjustments must be submitted no later than 12 months, or 1 calendar year, after the date the services were furnished.

Reference:  http://www.cgsmedicare.com/hhh/education/materials/timely_claim_filing_req.html

BLUE CROSS BLUE SHIELD:

Providers participating with BCBSNC are required to file FEP (Federal Employee Program) claims by December 31st of the calendar year, following the year in which the services were rendered or the date of discharge. Corrected claims must be submitted no later than one year (12 months) from the date of service. Section 4.12.4 of BCBS Manual

Claims for professional services provided to BlueCard® members having coverage with other Blue Plans (non-BCBSNC) must be submitted to BCBSNC within 180 days of providing service. Institutional/facility claims must be filed within 180 days of the member’s discharge date. Note: Providers contracted with BCBSNC are allowed 180 days for claim submissions to be eligible for benefits release.  However, members from other Blue Plans may have shorter filing time limitations applied depending on their individual benefit structure or State legal requirements.  Therefore, BCBSNC participating providers are encouraged to file claims for BlueCard® patients without delay.  Section 5.7.4 of BCBS Manual 

Note:  It is important to verify your payer's timely filing requirement, (during the admission process), as some payers have a much shorter window to submit claims.