Hi Navin,
If you are using the Table Browser to and the "CDS FASTA" output format,
then the CDS alignments from the UCSC Genes track (table: knownGene) are
in phase. If you are using RefSeq Genes (table: refGene), a few of the
refGene exons might not be in phase after the first exon since the mRNA
may have bases in it that aren't in the reference sequence, but the huge
majority will be in phase.
--
Brooke Rhead
UCSC Genome Bioinformatics Group